DESCRIPTION: The objective of these studies is to determine whether the exposure of experimental animals to 60Hz magnetic fields alters the degree of damage to DNA which is a normal consequence of exposure to a carcinogen. Carcinogens, in many cases, damage DNA because they induce the formation in cells of free radicals. Since it has been shown that magnetic fields increase the mean intracellular concentrations of free radicals, it is predicted that the combined treatments of rats with the carcinogen safrole (to generate large numbers of free radicals) plus their exposure to a 60Hz magnetic field will lead to greater damage to DNA that caused by a carcinogen only. To test these associations, carcinogen-treated rats will be exposed or sham-exposed to 60Hz magnetic fields for 8 hours (to stimulate duration of an occupational workday exposure). If magnetic field exposure increases DNA damage that results after carcinogen treatment, it could explain the means by which magnetic fields, although not directly carcinogenic, increase the incidence of cancer as reported in some epidemiological studies. Magnetic fields over a range of field strengths will be tested to identify possible dose-response relationships.